Choke assemblies are used to help regulate the pressure within a well as it is being drilled and stimulated. During such drilling, and particularly during stimulation, high pressure gases and drilling fluids may be propelled through the choke assembly, bringing sand and other debris which erode the interior of the choke assembly.
Typically, choke assemblies have a side inlet channel that feeds fluid into an upper body section of the choke. Within the upper body section, the flow is redirected through an upper body orifice to an end discharge channel. A shuttle assembly is retained by a bonnet located at the end of the upper body section opposite the end discharge channel. The shuttle assembly has a shuttle that may be selectively positioned to regulate the pressure of the flow through the upper body orifice. The selective positioning includes a seated position in which the flow is stopped prior to entering the end discharge channel.
Due to the high velocities of the flow through the choke assembly, sand and other debris that are carried with the flow quickly erode the interior of the upper body section of the choke assembly. Prior art attempts to protect the upper body section from excessive wear include long tubular projections from the bonnet of the choke assembly into the upper body section. While this technique provided some protection from damage to the upper body section, damage to the tubular projection would require replacement of the entire bonnet.
Another prior art method of protecting the upper body section of a choke assembly utilizes a type of sleeve insert wherein the entire sleeve fits within the upper body orifice of the upper body section to be protected. Such sleeve inserts have proven difficult to remove. As particles and drilling fluid accumulate in the small space between the upper body section wall and the outer surface of the wall, the sleeve becomes wedged within the upper body section. Because the entire sleeve is retained within the valve body it is difficult to grasp and remove the sleeve after wear due to erosion has been detected. It would be an improvement to the art to have a sleeve insert that is easier to remove and replace after sufficient wear on the component has been identified.